From patchwork Tue Aug 8 21:08:48 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Richard Henderson X-Patchwork-Id: 1819024 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256 header.s=google header.b=jxzsvTIU; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4RL5T90fHyz1yVt for ; Wed, 9 Aug 2023 07:11:09 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qTTwy-0007hJ-Bw; Tue, 08 Aug 2023 17:09:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qTTww-0007gT-Hw for qemu-devel@nongnu.org; Tue, 08 Aug 2023 17:09:06 -0400 Received: from mail-pl1-x635.google.com ([2607:f8b0:4864:20::635]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qTTwu-0005wH-Oz for qemu-devel@nongnu.org; Tue, 08 Aug 2023 17:09:06 -0400 Received: by mail-pl1-x635.google.com with SMTP id d9443c01a7336-1bbc87ded50so40538045ad.1 for ; Tue, 08 Aug 2023 14:09:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1691528943; x=1692133743; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=C24r9+7xFY76vv0xEMFFBjdertNUwY0/5sUwUC6qot0=; b=jxzsvTIUwdON3X3T34UwouL5ohKkmleedvZlccK4emcjw97hFXYJvaCl3Xq3YF8i3N 8oJpjo//9ckuQWNNkK8lUAoMEUUCWgUqPwS8RmZ19VRW4Iimy6xQASewuiUulPYPqRx1 ZhiB7hc/XCioHtV9x0LzFpdXVmm2QzyFW0vgJpEqyEbUtQRi1Kg7u+vZtcHbt3qYG/ik 9lJ1eO+SaiY5MeyfIbpx97FyaMnbUTQoVwNHqbWtX8tIIGk0UipurdwRxLEwwIw0RiUv 2K+cMe4W+hmxoIviYUAQsYX29fwYKnc4GIFz3V1Y0ax2/f2ABdJsOwZ6DV5w5Kw1wR2k gExQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691528943; x=1692133743; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=C24r9+7xFY76vv0xEMFFBjdertNUwY0/5sUwUC6qot0=; b=hoqkRwip/tC62NIDwIKnAmY3rdIetTuzSJ+ocKCu07f0tcVXz2XRH3+V9MTJA+woat 1h6kmKHbEaOEwAYiZo1aaVgI3Dk4dzN6ySaWBk+nNrZQfYKCqjPsMATO0+DLCDLN0CWz 39KtfswwZ8MlZfpVUddnw3OkNqQy4wjF/OAsPNrEQJ4MSKiSqM+kPhCSAyJOVQqaWVMG 1Bq1oaQ6fatJUFlfNTbtuLqT5uwWbiByj87uU1g50+dmIsZgkvZlcGj+Pzg9I1SrEYAc xYUCxHr+pKQMSUt44UHapyMod87QclOL2e8E/282f4H++dDTglhTY9OZSOLqCbjuZpjx gANw== X-Gm-Message-State: AOJu0YyusU9S7PK5WXMStSKb2p0E41Q1eKIJpkbMiJnd9W4T9q/nMPcY P4m4WVfjSZamdX3KdT9c8Esl9eAxuxkGP+/WHns= X-Google-Smtp-Source: AGHT+IESFwYZlzn3tmCGzduokTu6IlPdkEfnTxF4J9xMr/qM1EftFylQj+InWcpg9apIPiH1gg2+jg== X-Received: by 2002:a17:90a:c7c4:b0:268:f987:305d with SMTP id gf4-20020a17090ac7c400b00268f987305dmr674460pjb.5.1691528943582; Tue, 08 Aug 2023 14:09:03 -0700 (PDT) Received: from stoup.. ([2602:47:d490:6901:63dc:2a47:f4bc:4a95]) by smtp.gmail.com with ESMTPSA id k11-20020a170902694b00b001b3fb2f0296sm9437533plt.120.2023.08.08.14.09.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Aug 2023 14:09:03 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: Helge Deller , Akihiko Odaki , =?utf-8?q?Alex_Benn=C3=A9e?= Subject: [PULL 06/14] linux-user: Adjust initial brk when interpreter is close to executable Date: Tue, 8 Aug 2023 14:08:48 -0700 Message-Id: <20230808210856.95568-7-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230808210856.95568-1-richard.henderson@linaro.org> References: <20230808210856.95568-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::635; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x635.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Helge Deller While we attempt to load a ET_DYN executable far away from TASK_UNMAPPED_BASE, we are not completely in control of the address space layout. If the interpreter lands close to the executable, leaving insufficient heap space, move brk. Tested-by: Helge Deller Signed-off-by: Helge Deller [rth: Re-order after ELF_ET_DYN_BASE patch so that we do not "temporarily break" tsan, and also to minimize the changes required. Remove image_info.reserve_brk as unused.] Reviewed-by: Akihiko Odaki Reviewed-by: Alex Bennée Signed-off-by: Richard Henderson --- linux-user/qemu.h | 1 - linux-user/elfload.c | 51 +++++++++++++------------------------------- 2 files changed, 15 insertions(+), 37 deletions(-) diff --git a/linux-user/qemu.h b/linux-user/qemu.h index 2046a23037..4f8b55e2fb 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -30,7 +30,6 @@ struct image_info { abi_ulong start_data; abi_ulong end_data; abi_ulong brk; - abi_ulong reserve_brk; abi_ulong start_mmap; abi_ulong start_stack; abi_ulong stack_limit; diff --git a/linux-user/elfload.c b/linux-user/elfload.c index d1b278d799..3553a3eaef 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -3110,27 +3110,6 @@ static void load_elf_image(const char *image_name, int image_fd, load_addr = loaddr; if (pinterp_name != NULL) { - /* - * This is the main executable. - * - * Reserve extra space for brk. - * We hold on to this space while placing the interpreter - * and the stack, lest they be placed immediately after - * the data segment and block allocation from the brk. - * - * 16MB is chosen as "large enough" without being so large as - * to allow the result to not fit with a 32-bit guest on a - * 32-bit host. However some 64 bit guests (e.g. s390x) - * attempt to place their heap further ahead and currently - * nothing stops them smashing into QEMUs address space. - */ -#if TARGET_LONG_BITS == 64 - info->reserve_brk = 32 * MiB; -#else - info->reserve_brk = 16 * MiB; -#endif - hiaddr += info->reserve_brk; - if (ehdr->e_type == ET_EXEC) { /* * Make sure that the low address does not conflict with @@ -3221,7 +3200,8 @@ static void load_elf_image(const char *image_name, int image_fd, info->end_code = 0; info->start_data = -1; info->end_data = 0; - info->brk = 0; + /* Usual start for brk is after all sections of the main executable. */ + info->brk = TARGET_PAGE_ALIGN(hiaddr); info->elf_flags = ehdr->e_flags; prot_exec = PROT_EXEC; @@ -3315,9 +3295,6 @@ static void load_elf_image(const char *image_name, int image_fd, info->end_data = vaddr_ef; } } - if (vaddr_em > info->brk) { - info->brk = vaddr_em; - } #ifdef TARGET_MIPS } else if (eppnt->p_type == PT_MIPS_ABIFLAGS) { Mips_elf_abiflags_v0 abiflags; @@ -3646,6 +3623,19 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info) if (elf_interpreter) { load_elf_interp(elf_interpreter, &interp_info, bprm->buf); + /* + * While unusual because of ELF_ET_DYN_BASE, if we are unlucky + * with the mappings the interpreter can be loaded above but + * near the main executable, which can leave very little room + * for the heap. + * If the current brk has less than 16MB, use the end of the + * interpreter. + */ + if (interp_info.brk > info->brk && + interp_info.load_bias - info->brk < 16 * MiB) { + info->brk = interp_info.brk; + } + /* If the program interpreter is one of these two, then assume an iBCS2 image. Otherwise assume a native linux image. */ @@ -3699,17 +3689,6 @@ int load_elf_binary(struct linux_binprm *bprm, struct image_info *info) bprm->core_dump = &elf_core_dump; #endif - /* - * If we reserved extra space for brk, release it now. - * The implementation of do_brk in syscalls.c expects to be able - * to mmap pages in this space. - */ - if (info->reserve_brk) { - abi_ulong start_brk = TARGET_PAGE_ALIGN(info->brk); - abi_ulong end_brk = TARGET_PAGE_ALIGN(info->brk + info->reserve_brk); - target_munmap(start_brk, end_brk - start_brk); - } - return 0; }